Magnetic resonance-guided high intensity focused ultrasound (MRgHIFU) is being explored as a non-invasive technology to treat solid tumors. However, the clinical use of HIFU for tumor ablation applications is currently limited by the long treatment times required. Phase-shift nanoemulsions (PSNE), consisting of liquid perfluorocarbon droplets that can be vaporized into microbubbles, are being developed to accelerate HIFU-mediated heating. The purpose of this study was to examine accumulation of PSNE in intramuscular rabbit tumors in vivo. MR images were acquired before and after intravenous injection of gadolinium-containing PSNE. MR signal enhancement was observed in rabbit tumors up to six hours after injection, indicating that PSNE accumulated in the tumors. In addition, PSNE vaporization was detected in the tumor with B-mode ultrasound imaging, and MR thermometry measurements indicated that PSNE accelerated the rate of HIFU-mediated heating. These results suggest that PSNE could dramatically improve the efficiency and clinical feasibility of MRgHIFU.
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http://dx.doi.org/10.1260/2040-2295.4.1.109 | DOI Listing |
Nanomaterials (Basel)
August 2021
Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN 47907, USA.
Liquid perfluorocarbon-based nanodroplets are stable enough to be used in extravascular imaging, but provide limited contrast enhancement due to their small size, incompressible core, and small acoustic impedance mismatch with biological fluids. Here we show a novel approach to overcoming this limitation by using a heating-cooling cycle, which we will refer to as thermal modulation (TM), to induce echogenicity of otherwise stable but poorly echogenic nanodroplets without triggering a transient phase shift. We apply thermal modulation to high-boiling point tetradecafluorohexane (TDFH) nanodroplets stabilized with a bovine serum albumin (BSA) shell.
View Article and Find Full Text PDFAdv Colloid Interface Sci
August 2021
Harangoutte Institute, 68160 Ste Croix-aux-Mines, France.
After the protocol-related indecisive clinical trial of Oxygent, a perfluorooctylbromide/phospholipid nanoemulsion, in cardiac surgery, that often unduly assigned the observed untoward effects to the product, the development of perfluorocarbon (PFC)-based O nanoemulsions ("blood substitutes") has come to a low. Yet, significant further demonstrations of PFC O-delivery efficacy have continuously been reported, such as relief of hypoxia after myocardial infarction or stroke; protection of vital organs during surgery; potentiation of O-dependent cancer therapies, including radio-, photodynamic-, chemo- and immunotherapies; regeneration of damaged nerve, bone or cartilage; preservation of organ grafts destined for transplantation; and control of gas supply in tissue engineering and biotechnological productions. PFC colloids capable of augmenting O delivery include primarily injectable PFC nanoemulsions, microbubbles and phase-shift nanoemulsions.
View Article and Find Full Text PDFJ Ultrasound Med
January 2022
Nuffield Department of Surgical Sciences, University of Oxford, Oxford, UK.
Purpose: To investigate whether phase-shift perfluoropetane (PFP) nanoemulsions can enhance pulsed high-intensity focused ultrasound (HIFU) ablation.
Methods: PFP was encapsulated by poly(lactic-co-glycolic acid) (PLGA) to form a nanometer-sized droplet (PLGA-PFP), which was added to an isolated perfused liver system. Meanwhile, phosphate-buffered saline (PBS) was used as a control.
Ultrasound Med Biol
August 2019
Department of Biomedical Engineering, Boston University, Boston, Massachusetts, USA.
High intensity focused ultrasound (HIFU) mechanical ablation is an emerging technique for non-invasive transcranial surgery. Lesions are created by driving inertial cavitation in tissue, which requires significantly less peak pressure and time-averaged power compared with traditional thermal ablation. The utility of mechanical ablation could be extended to the brain provided the pressure threshold for inertial cavitation can be reduced.
View Article and Find Full Text PDFUltrasound Med Biol
March 2019
Department of Mechanical Engineering, Boston University, Boston, Massachusetts, USA; Department of Biomedical Engineering, Boston University, Boston, Massachusetts, USA. Electronic address:
Acoustic cavitation can be used to temporarily disrupt cell membranes for intracellular delivery of large biomolecules. Termed sonoporation, the ability of this technique for efficient intracellular delivery (i.e.
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